Device for cutting open letter envelopes

ABSTRACT

A device for cutting open letter envelopes comprises a guideway which includes a support surface over which the letter envelopes are moved and a lateral surface along which they are guided. The support surface has a longitudinal slot extending substantially parallel to the lateral guide surface and an endless belt conveyor extends with its upper reach through the slot to engage the envelopes and to advance them along the support surfaces. A pair of opposed cooperable rotary cutter blades define a nip therebetween which is aligned with the support surface so that the envelopes are directed between the nip and are cut open as they are moved. The top one of the cutter blades is mounted so that the blade may be shifted laterally in order to vary the plane of cutting which it effects in cooperation with the lower counter-roller which is wider than the upper roller and which is driven by a driving motor. A pivotal sensor engages the envelopes which are fed by the conveyor and is moved in response to the thickness of the envelope or the variations of its thickness to cause a shifting of the upper roller blade in order to vary the cutting plane thereof in accordance with the letter which is being advanced.

United States Patent 1 Hang g [451 Feb. 25, 1975 DEVICE FOR CUTTING OPENLETTER ENVELOPES [75] Inventor: Werner Hang, Langnau, Switzerland [73]Assignee: Frama A.G., Luperswil, Switzerland [22] Filed: Oct. 5, I973211 App]. No.: 404,012

[30] Foreign Application Priority Data Oct. 9, 1972 Switzerland 14749/72[52] [1.8. CI 83/368, 83/499, 83/912 [51] Int. Cl B43m 7/00 [58] Fieldof Search 83/368, 912, 499

[56] References Cited UNITED STATES PATENTS 2,027,045 1/1936 Keiser83/912 X Primary ExaminerJ. M. Meister Attorney, Agent, or FirmMcGlewand Tuttle [57] ABSTRACT A device for cutting open letter envelopescomprises a guideway which includes a support surface over which theletter envelopes are moved and a lateral surface along which they areguided. The support surface has a longitudinal slot extendingsubstantially parallel to the lateral guide surface and an endless beltconveyor extends with its upper reach through the slot to engage theenvelopes and to advance them along the support surfaces. A pair ofopposed cooperable rotary cutter blades define a nip therebetween whichis aligned with the support surface so that the envelopes are directedbetween the nip and are cut open as they are moved. The top one of thecutter blades is mounted so that the blade may be shifted laterally inorder to vary the plane of cutting which it effects in cooperation withthe lower counter-roller which is wider than the upper roller and whichis driven by a driving motor. A pivotal sensor engages the envelopeswhich are fed by the conveyor and is moved in response to the thicknessof the envelope or the variations of its thickness to cause a shiftingof the upper roller blade in order to vary the cutting plane thereof inaccordance with the letter which is being advanced.

12 Claims, 5 Drawing Figures PATENTEDFEB25 1% 3'. 867, 860

SHEET 2 OF 2 EQQ i 27 DEVICE FOR CUTTING OPEN LETTER ENVELOPES FIELD ANDBACKGROUND OF THE INVENTION This invention relates in general to letteropening devices and, in particular, to a new and useful device forcutting open letter envelopes which includes means for feeding envelopesin succession between two cooperating cutting rollers and with means forsensing the thickness of the envelopes and shifting the cutting rollersaccordingly for the purpose of varying the plane of cutting inaccordance with the envelope being handled.

DESCRIPTION OF THE PRIOR ART In the known envelope opening devices,there is usually some means to permit adjustment of the device toaccommodate letters of different thicknesses but this adjustment must bemade manually by displacing a pressure disc engaged on a thread andmoving it through a predetermined angle so that the pair of blades whicheffects the cutting are moved away from the lateral guide for theenvelopes into a more distant plane. However, because the letters to beopened are usually of unequal thicknesses, such devices require a greatdeal of manual operation, or the letters must be processed in accordancewith size and thickness in separate groups.

SUMMARY OF THE INVENTION In accordance with the present invention, thedraw backs of the prior art are eliminated and there is provided anautomatic device for feeding envelopes between the nip of cooperatingrollers which are adjusted in accordance with the size of each envelopewhich is fed. The arrangement includes a sensing member which is mountedso as to engage each envelope which is being fed and which is connectedto shift one of a pair of cooperative blades which engage the envelopeto cut it open. The sensing member is moved in an amount comparable tothe letter thickness and it is connected through a combined lever anddisc member to shift the cutting blade axially and laterally in respectto the guide surface by an amount comparable to any change in thicknessof the envelope being processed. The arrangement is such that thedistance of one of the cutting rollers from the plane of the lateralguide wall is changed as a function of the displacement of the sensingmember which is displaced in accordance with the thickness of eachenvelope which is fed.

Accordingly, it is an object of the invention to provide a device forcutting open letter envelopes which includes means for feeding letterenvelopes in succession between the nip of cooperating rollers whichincludes at least one having means for shifting it axially to adjust itscutting plane position in respect to a guidewall for the envelopes andwhich also includes means for sensing each envelope as it is fed so thatthe cutting blade is shifted by an amount to ensure that the cuttingplane is properly set for the particular thickness of the envelope beingfed.

A further object of the invention is to provide a letter opening devicewhich is simple in design, rugged in construction and economical tomanufacture.

For an understanding of the principles of the invention, reference ismade to the following description of a typical embodiment thereof asillustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings: Q

FIG. 1 is a side elevational view of an envelope cutting deviceconstructed in accordance with the invention;

FIG. 2 is a top plan view of the device shown in FIG.

FIG. 3 is a partial sectional view of the adjustable mounting for thenon-driven upper cutting blade shown in FIG. 1;

FIG. 4 is a plan view of one of the adjustment members for varying theposition of a cutting blade; and

FIG. 5 is a plan view of a combined lever disc blade positioning controlmember for shifting the position of the cutting blade.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to thedrawings in particular, the invention embodied therein, comprises anenvelope feeding and opening device in which a plurality of letters orenvelopes are supplied from the lefthand side of the machine shown inFIG. 1 in the direction of the arrow 1 so that they ar either placed onor fed into the left portion of the guideway, generally designated 2.

In accordance with the invention, the guideway 2 includes a supportsurface 4 over which the envelopes are fed and which is substantiallyperpendicular to a guide surface 5 against which they bear as they aremoved. The envelopes are moved or fed when they come into contact with aconveying belt 3 having an upper reach which projects through a slot 9defined in the support surface 4 and extending longitudinally therealongsubstantially parallel to the guide wall 5. The envelopes may be fedmanually or by means of a mechanism (not shown) for removing them from astacking container. Generally speaking, it is preferable that thefeeding surface or support surface 4 be slightly inclined downwardlytoward the guide wall 5 so that the envelopes will slip on the feedingsurface due to gravity and the edge will move into lateral engagementwith the guide wall 5 and move along this wall during the action of theconveying belt 3.

In the embodiment indicated, the conveying belt comprises an endlesscircular cross-section member trained around two spaced apart pulleys 6,7, which are mounted below the guideway 2. The righthand pulley 7 isdriven by a motor having a shaft 16 with a small diameter pulley 17which drives through a pulley belt 13, a larger diameter pulley 14 on ashaft 15. The pulley 7 is also connected on the shaft 15. The upperreach of endless conveyor 3 projects through slot 9 defined in thesupport 4. The envelopes are engaged frictionally by the endless belt 3which protrudes slightly above the surface of support 4 so that belt 3comes into contact with the envelopes and advances them by frictionalengagement up to the end of the guideway.

A pair of cutting blades, including a lower cutting blade orcounterblade 11, which is affixed to shaft 15 for rotation therewith,and an upper blade 10 which is of a narrower width than the blade 11 arearranged adjacent to and substantially parallel to the end guide 5 andthey define a cutting plane 12 which may be shifted toward and away fromthe guide 5 in accordance with the width of the envelopes being handled.The shaft 15 which is driven from the motor 50 carries both the lowercutting blade 11 and a pulley 7 and it is mounted below fixed support 4on the front side of housing wall 8. The blades 10 and 11 operate inalignment with a longitudinally extending slot 19 of the support 4.

A circular cutout 18 is provided in the guide wall for the upper cuttingblade 10. Lower cutting blade 11 protrudes into guide way 2 and itscarrying shaft 15 is biased by a spring (not shown) in a direction tourge the lower cutting blade 11 upwardly into cooperative engagementwith the upper cutting blade 10. The two blades are always superposedand cooperate with each other as a cutting tool.

In accordance with the invention, there is a separate drrive for upperblade which is not shown but which, for example, may comprise a separatedrive motor with a belt or friction roller transmission connection or aconnection by a belt off the shaft which drives the lower blade 11.

In accordance with a further feature of the invention, the upper blade10 is mounted for axial adjustment in order to vary the position of thecutting plane 12 and this mechanism is indicated in detail in FIG. 3.The cutting blade 10 is secured to a casing block 20 which is rigidlyfixed, for example, by being press-fitted to a shaft 21. Casing block 20is made hollow on the side opposite to blade 10, and it encloses athrust bearing 22 which includes a bearing disc 24 which applies againstthe inner surface of casing block 20 and another hearing disc 24 whichmay apply directly or as indicated, indirectly, through an intermediatedisc 26 against a lever actuator disc which during the cutting operationis immobile. Radial slide bearings 27 and 28 provide a mounting for theshaft 21 in a supporting block 29 and they are affixed to a back wall 30of the housing which extends parallel to the guide wall 5. An extensionsleeve 31 is also mounted in the block 29 and it has an external threadwhich is threaded to the opening provided in the backwall 30. Anadjusting disc 32 is also threaded on the exterior of the sleeve 3l. Thecircumference of the adjusting disc 32 is provided with a plurality ofnotches 33 and a pawl 34 which is affixed to the back wall 30 engages inone of the notches so as to prevent the disc from an unintentionalturning. The pawl is movable so as to permit it to become disengagedfrom the notches 33 when rotation of the disc 32 and adjustment of itsaxial position is desired. The adjustment of the disc 32 permits a basicadjustment of the cutting plane 12 relative to the lateral guide wall 5.This adjustment is effected by moving pawl 34 out of notch 33 and thenturning disc 32 on threaded sleeve 31, for example, by an incrementalamount which, as shown in FIG. 4, may be as small as a 45 turn. The disc32 is then locked into position again by means of pawl 34. The axialdisplacement which results from the turning of the adjusting disc 32 istransferred by means of the thrust bearing 22 to the casing block 20 andthereby to cutting blade 10 so that the entire assembly, comprising thecutting blade 10, casing block 20 and shaft 21 is axially displaced inthe bearings 27 and 28. A back movement of this assembly from the newposition is prevented by the resilient pressure of cutting blade 11against the upper cutting blade 10.

In order to permit not only a basic adjustment of the cutting plane 12by means of the adjusting disc 32, but also an automatic immediateadjustment to accommodate letters having irregular thicknesses, theinvention includes a further means for effecting an automatic adjustmentin accordance with the thickness of the envelope which is being passedthrough the device. The mechanism includes a lever actuator disc 25, asshown in FIG. 5, which is pivotally mounted between thrust bearing 22and adjusting disc 32. The disc 25 includes a lever portion 25a and arotary motion of this lever actuator disc 25 produced by a slightdisplacement of a channel-shaped sensing lever 35 from its zero positionwhich is caused by the passage of a letter which is thicker than theprevious letter, results in an axial pressure against the thrust bearing22, and thereby, in a displacement of the cutting blade 10. Cam-likeelevations in the form of balls 36 engage into flat flaring recesses 37of adjusting disc 32. Recesses 37 are impressed in disc 25 and havesubstantially V-shape cross-sections. The flare-shaped surfaces ofrecesses 37 form, for example, an angle of 20 with the main surface ofthe disc. As soon as lever 25a of the disc 25 is slightly turned by theaction of the sensor member 35 which rides on the letter passing overthe belt 3, the cam balls 36 are displaced along the sloping surfaces ofrecesses 37, so that the disc 25 is moved away from the locked adjustingdisc 32 in the direction of thrust bearing 22 so that cutting blade 10is axially displaced to accommodate the letter of thicker proportions.

Sensing lever 01' sensor 35 is pivotally mounted adjacent its righthandend on pin 38, as shown in FIG. 1, which is rigidly fixed between walls30 and 5, as shown in FIG. 2. Pin 38 passes through the two legs 39 and40 of the channel-shaped sensor 35 and a cross-pin 41 is rigidly fixedto pin 38 and extends perpendicularly thereto so that it lays along andbelow the web portion 42 of sensing lever 35. A screw 43 is threadedthrough web portion 42 of sensor 35 above cross-pin 41 and the end ofthe screw applies against the cross-pin 41 so that upon turning of screw43, the sensing lever 35 is displaced by a small angle and its zeroposition is thus adjusted.

As shown in FIG. 2, sensor 35 extends above a part of conveying belt 3so that a letter or envelope advanced through the device passes belowthe sensor 35. The spacing of the legs of the channel-shaped sensor 35and their location, are chosen so that the legs 39 and 40 are positionedso that they are laterally spaced above belt 3. The zero position ofsensor 3 is adjusted so that only a letter of considerable thicknesswould cause an automatic adjustment of the cutting plane 12 and adisplacement of sensor 35 upwardly. Letters of smaller thicknesses arecut open in a plane which has been appropriately adjusted as the basicor zero position with respect to the lateral guide wall 5 and by turningand locking adjusting disc 32.

Sensing lever 35 is connected by means of a transverse pin 44 to thefree end of the lever portion 250 of lever-actuated disc 25, as shown inFIG. 2. Transverse pin 44 extends through a slot (not shown) which isprovided in lateral guide wall 5 and the pin engages into a longitudinalslot 46 of lever portion 250 of leveractuated disc 25. In order topermit a particularly effortless displacing of the sensing lever 35, andthereby an easy turning of the lever-actuated disc 25, a tension spring47 is attached, in the present example, to the end of lever portion 25aand the other end of spring 47 is fixed to pin 50 which is secured toback wall 30. Spring 47 compensates for the weight of sensing lever 35and may be adjusted so as to give the lever a small bias in theclockwise direction. This bias must be small enough so as not to cause aturning of the lever-actuated disc 25 and thereby, a displacement of thecutting plane 12.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understoood that the invention may be embodiedotherwise without departing from such principles.

I claim:

1. A device for cutting open envelopes, comprising means defining aguideway for envelopes, a motor driven conveying mechanism providedalong said guideway engageable with the envelopes for moving them alongsaid guideway, a pair of cooperative cutting blades arranged inopposition along said guideway and defining a cutting plane, saidcutting plane being adjustable in respect to a side of said guideway,said guideway serving to guide the envelope edges to be cut open so thatthey are moved between said cutting blades, a sensing member engageablewith each letter moved by said conveying mechanism along said guidway,an adjustment mechanism for the pair of cutting blades for shifting atleast one of said blades laterally and being connected to said sensingmember and actuated by displacement of said sensing member by thetransported envelope according to the thickness thereof to vary theposition of said cutting blades so that the distance of the cuttingplane is changed as a function of the sensing member displacement.

2. A device for cutting open envelopes, according to claim 1, whereinsaid sensing member comprises a lever member pivoted at its trailing endand having a forward end overlying said conveyor which is movableupwardly and downwardly, an upper cutting blade rotatable shaft affixedto said cutting blade and being mounted for axial displaceable movementand a control member connected to said shaft and connected to said levermember being responsive to movement of said lever member to shift saidshaft axially whereby to vary the position of said cutting blade on saidshaft in accordance with the thickness of the envelope which is movedover said conveyor belt.

3. A device for cutting open envelopes, according to claim 2, whereinsaid adjusting member comprises a disc surrounding said shaft and havinga lever portion connected to said sensing member, an adjustment disc onsaid shaft being fixable in a fixed location axially, ball cam meansdisposed between said adjustment disc and said control disc having saidlever arm portion, said control disc having at least one recess carryingsaid ball cam means with sloping surfaces extending from the recessupwardly to the surface of said disc, said ball cam means beingshiftable up the surface of said disc when said lever portion is movedto rotate said disc whereby to shift said disc axially to shift saidcutting blade thereby.

4. A device for cutting open letter envelopes, comprising a guidewayhaving a support surface over which the letter envelopes are moved and alateral surface along which they are guided, said support surface havinga longitudinal slot extending substantially parallel to said lateralguide surface, a movable conveyor having an upper reach aligned with theslot and projecting above the support surface to engage envelopesthereon for moving them along said support surface, a pair of opposedcooperable rotary cutter blades having a nip therebetween aligned withsaid support so that the envelopes which are moved by said conveyor aredirected therebetween as they are guided by said lateral guide surface,adjustment means connected to at least one of said rotary cutter bladesfor shifting said one of said rotary cutter blades laterally for varyingthe cutting plane thereof, the other of said rotary cutter blades beingwide enough to remain in cooperative engagement with said upper rotarycutter blades while the one rotary cutter blade is adjusted to vary thecutting plane position in respect to said lateral guidle surface, and asensor overlying said suport surface engageable with the envelopesmovable therealong and connected to said adjustment means to causeshifting of said at least one of said rotary cutter blades for varyingthe cutting plane in accordance with the thickness of the envelope whichis sensed.

5. A device for cutting open letter envelopes, according to claim 4,including a shaft rotatably supporting said one of said rotary cutterblades which is axially adjustable, bearing means supporting said shaftfor axial displacement, a thrust bearing surrounding said shaftincluding a positioning member which is adapted to be fixed in position,an adjusting member spaced axially from said fixed member, cam meanslocated between said adjusting member and said fixed member, said sensorincluding a sensing member connected to said adjusting member which isdisplaceable in accordance with the thickness of the envelopes being fedto rotate said adjusting member to shift said cam means so as to shiftsaid adjusting member axially along with said one of said rotary cutterblades.

6. A device for cutting open letter envelopes, according to claim 4,wherein said fixed member comprises a disc mounted on said cutter bladeshaft, said adjustment member comprises an actuation disc having a leverarm portion rotatably mounted around said shaft, said sensorcomprising amember overlying said guideway and engageable with the letters beingpassed therealong and being connected to said lever to rotate it withsaid disc portion and to cause said cam means to effect axialdisplacement thereof along with said rotary blade.

7. A device for cutting open letter envelopes, accord ing to claim 6,wherein said sens-or comprises a lever having a trailing end pivotallymounted above said guideway and having a forward end overlying saidguideway and engageable with the envelopes movable thereon, anequalizing spring connected to said forward end and holding said forwardend above said guideway, and a zero adjustment mechanism connected tosaid lever sensor for adjusting its zero position.

8. A device for cutting open letter envelopes, according to claim 6,wherein at least one of said fixed member discs and said adjustingmember disc having said lever portion is provided with at least onerecess on the side facing the other member having sloping surfacesextending outwardly from the recess toward the surface of said disc,said cam means comprising a ball arranged in the recess and bearing inthe recess on the other associated adjacent disc, said ball beingdisplaceable out of said recess to shift the members apart to vary theposition of said blade.

9. A device for cutting open letter envelopes, according to claim 8,wherein said recesses have a V-shape cross-section.

10. A device for cutting open letter envelopes, according to claim 4,wherein said conveyor comprises a round cross-section endless belt, saidsensor comprising a lever pivotally mounted adjacent one end overendless belt.

12. A device for cutting open letter envelopes, according to claim 4,including a separate drive shaft for each of said upper and lower rotarycutting blades,

each of which are driven.

1. A device for cutting open envelopes, comprising means defining aguideway for envelopes, a motor driven conveying mechanism providedalong said guideway engageable with the envelopes for moving them alongsaid guideway, a pair of cooperative cutting blades arranged inopposition along said guideway and defining a cutting plane, saidcutting plane being adjustable in respect to a side of said guideway,said guideway serving to guide the envelope eDges to be cut open so thatthey are moved between said cutting blades, a sensing member engageablewith each letter moved by said conveying mechanism along said guidway,an adjustment mechanism for the pair of cutting blades for shifting atleast one of said blades laterally and being connected to said sensingmember and actuated by displacement of said sensing member by thetransported envelope according to the thickness thereof to vary theposition of said cutting blades so that the distance of the cuttingplane is changed as a function of the sensing member displacement.
 2. Adevice for cutting open envelopes, according to claim 1, wherein saidsensing member comprises a lever member pivoted at its trailing end andhaving a forward end overlying said conveyor which is movable upwardlyand downwardly, an upper cutting blade rotatable shaft affixed to saidcutting blade and being mounted for axial displaceable movement and acontrol member connected to said shaft and connected to said levermember being responsive to movement of said lever member to shift saidshaft axially whereby to vary the position of said cutting blade on saidshaft in accordance with the thickness of the envelope which is movedover said conveyor belt.
 3. A device for cutting open envelopes,according to claim 2, wherein said adjusting member comprises a discsurrounding said shaft and having a lever portion connected to saidsensing member, an adjustment disc on said shaft being fixable in afixed location axially, ball cam means disposed between said adjustmentdisc and said control disc having said lever arm portion, said controldisc having at least one recess carrying said ball cam means withsloping surfaces extending from the recess upwardly to the surface ofsaid disc, said ball cam means being shiftable up the surface of saiddisc when said lever portion is moved to rotate said disc whereby toshift said disc axially to shift said cutting blade thereby.
 4. A devicefor cutting open letter envelopes, comprising a guideway having asupport surface over which the letter envelopes are moved and a lateralsurface along which they are guided, said support surface having alongitudinal slot extending substantially parallel to said lateral guidesurface, a movable conveyor having an upper reach aligned with the slotand projecting above the support surface to engage envelopes thereon formoving them along said support surface, a pair of opposed cooperablerotary cutter blades having a nip therebetween aligned with said supportso that the envelopes which are moved by said conveyor are directedtherebetween as they are guided by said lateral guide surface,adjustment means connected to at least one of said rotary cutter bladesfor shifting said one of said rotary cutter blades laterally for varyingthe cutting plane thereof, the other of said rotary cutter blades beingwide enough to remain in cooperative engagement with said upper rotarycutter blades while the one rotary cutter blade is adjusted to vary thecutting plane position in respect to said lateral guide surface, and asensor overlying said suport surface engageable with the envelopesmovable therealong and connected to said adjustment means to causeshifting of said at least one of said rotary cutter blades for varyingthe cutting plane in accordance with the thickness of the envelope whichis sensed.
 5. A device for cutting open letter envelopes, according toclaim 4, including a shaft rotatably supporting said one of said rotarycutter blades which is axially adjustable, bearing means supporting saidshaft for axial displacement, a thrust bearing surrounding said shaftincluding a positioning member which is adapted to be fixed in position,an adjusting member spaced axially from said fixed member, cam meanslocated between said adjusting member and said fixed member, said sensorincluding a sensing member connected to said adjusting member which isdisplaceable in accordance with the thickness of the envelopes being fedto rOtate said adjusting member to shift said cam means so as to shiftsaid adjusting member axially along with said one of said rotary cutterblades.
 6. A device for cutting open letter envelopes, according toclaim 4, wherein said fixed member comprises a disc mounted on saidcutter blade shaft, said adjustment member comprises an actuation dischaving a lever arm portion rotatably mounted around said shaft, saidsensor comprising a member overlying said guideway and engageable withthe letters being passed therealong and being connected to said lever torotate it with said disc portion and to cause said cam means to effectaxial displacement thereof along with said rotary blade.
 7. A device forcutting open letter envelopes, according to claim 6, wherein said sensorcomprises a lever having a trailing end pivotally mounted above saidguideway and having a forward end overlying said guideway and engageablewith the envelopes movable thereon, an equalizing spring connected tosaid forward end and holding said forward end above said guideway, and azero adjustment mechanism connected to said lever sensor for adjustingits zero position.
 8. A device for cutting open letter envelopes,according to claim 6, wherein at least one of said fixed member discsand said adjusting member disc having said lever portion is providedwith at least one recess on the side facing the other member havingsloping surfaces extending outwardly from the recess toward the surfaceof said disc, said cam means comprising a ball arranged in the recessand bearing in the recess on the other associated adjacent disc, saidball being displaceable out of said recess to shift the members apart tovary the position of said blade.
 9. A device for cutting open letterenvelopes, according to claim 8, wherein said recesses have a V-shapecross-section.
 10. A device for cutting open letter envelopes, accordingto claim 4, wherein said conveyor comprises a round cross-sectionendless belt, said sensor comprising a lever pivotally mounted adjacentone end over said guideway and having an opposite end disposed tooverlie said belt so that the advanced envelopes pass between the beltand the bottom of said sensing lever.
 11. A device for cutting openletter envelopes, according to claim 10, wherein said lever is ofchannel-shape cross-section having spaced apart legs spaced by a widthapproximately equal to the diameter of said endless belt.
 12. A devicefor cutting open letter envelopes, according to claim 4, including aseparate drive shaft for each of said upper and lower rotary cuttingblades, each of which are driven.